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Article XV. 



Second Series of ExjJeriments on the Expansion of Dry Air 

 between 0° and 100°. By the late Professor F. Rudberg. 

 [From Poggendorff's Annalen, B. 44. S. 119.] 



Since the publication of my experiments on the expansion of 

 air (Poggendorff^s Annalen, B. 41 . S. 2']\.), I have had an appa- 

 ratus constructed, by the aid of which one such experiment may 

 be made in the short space of an hour and a half, or two hours. 

 The mean of the results which it has given agree perfectly with 

 those I had previously obtained. I here communicate a short 

 description of the apparatus, and the values of the expansion 

 which it has afforded. 



The construction of the apparatus enables us to determine 

 the pressures of a given mass of dry air at 0° and at 100°, the 

 spaces occupied by the air in 

 the two cases differing only by 

 the expansion of the receiver. 



The dry air is contained in 

 the cylinder A B, m hich com- 

 municates through the slen- 

 der tube DE with the wide 

 tube F, which, together with 

 a second tube H I, about 50 

 centimetres long, and open at 

 both ends, is cemented into 

 the Ud of the box G. The 



box contains a leathern bag ^A 



for holding mercury, the ca- ^- 



pacity of which, as in a baro- 

 meter,can be altered by means 

 of the screw K, so that the 

 mercury may be elevated or 

 depressed in ihe tubes. A 

 fine line is traced v, ith a dia- 

 mond point on the slender 

 tube D E at C, up to which 

 the mercuiy is screwed, as 



